Field of the Invention
The disclosure generally relates to control systems for a lift axle, or lift axles, in a two-or-more suspension for wheeled vehicles, including trucks and trailers.
Description of Related Art
Multi-axle suspensions, commonly found on trucks and trailers and related vehicles, generally have suspension systems that allow for selective raising and lowering of one axle relative to the other axles. The axle that is raised and lowered is known in the art as a lift axle.
When the lift axle is lowered, its wheels engage the road surface or other terrain, thereby enabling the lift axle's wheels to bear some of the vehicle weight and, in turn, relieving the other axles' wheels from some of the vehicle weight they would otherwise bear. When the lift axle is raised, its wheels disengage the underlying surface and, when disengaged, the raised wheels no longer assist in bearing the vehicle's weight.
Among the factors in the decision to raise or lower a lift axle is the total vehicle load. This information may be obtained from a number of sources as is known in the art. Generally, if the vehicle load is of a weight that is greater than a predetermined threshold weight, a decision may be made, either manually or automatically, to lower the lift axle to assist in weight bearing. If the vehicle load weight is below a predetermined threshold weight, the decision may be made, either manually or automatically, to raise the lift axle to assist in, inter alia, fuel consumption and tire wear on the lift axle tires.